Abstract: A method, algorithm, circuits, and/or systems for demodulation in an amplitude modulated (AM) radio receiver are disclosed. In one embodiment, a radio receiver can include an amplifier configured to receive a radio frequency (RF) input signal and a gain control signal, and provide an amplified signal, an automatic gain control (AGC) circuit configured to receive a high threshold comparator output and provide the gain control signal, a mixer configured to combine the amplified signal and a local oscillation signal and provide a mixed output, a high threshold comparator configured to compare the mixed output with a reference level and provide the high threshold comparator output, and a low threshold comparator configured to compare the mixed output with the reference level and provide an output of the radio receiver.

Abstract: A method, algorithm, architecture, circuits, and/or systems for squelch detection in serial communications are disclosed. In one embodiment, a squelch detector can include: (i) a first comparator having first and second inputs configured to receive a differential signal, and a third input configured to receive a signal substantially derived from the differential signal, where the first comparator can provide a comparator output; and (ii) a second comparator that can receive the comparator output and a reference voltage, and may provide a logic level squelch indication. The third input signal may be a common reference signal that is approximately an average voltage of the differential signal, for example. The first comparator may comprise a three-input comparator and the second comparator may comprise a two-input hysteresis comparator, for example. Embodiments of the present invention can advantageously provide a reliable and simplified approach for squelch detection in serial communication applications.

Abstract: A method, algorithm, circuits, and/or systems for automatic gain control (AGC) are disclosed. In one embodiment, an AGC circuit can include a comparator configured to compare an output of an amplifier against a reference voltage, gain logic configured to decrease a gain of the amplifier when an output of the comparator has a first state, and to periodically increase the gain of the amplifier, a digital-to-analog converter (DAC) configured to receive an output from the gain logic and control the gain of the amplifier, and lock detection logic configured to determine from the output of the gain logic when the gain of the amplifier is in a predetermined range.

Abstract: A method, algorithm, circuits, and/or systems for automatic gain control (AGC) are disclosed. In one embodiment, an AGC circuit can include a comparator configured to compare an output of an amplifier against a reference voltage, gain logic configured to decrease a gain of the amplifier when an output of the comparator has a first state, and to periodically increase the gain of the amplifier, a digital-to-analog converter (DAC) configured to receive an output from the gain logic and control the gain of the amplifier, and lock detection logic configured to determine from the output of the gain logic when the gain of the amplifier is in a predetermined range.

Abstract: A method, algorithm, architecture, circuits, and/or systems for low noise amplification are disclosed. In one embodiment, an amplifier can include an input stage, including a first differential input configured to receive a differential signal, a first current source coupled to the first differential input, a first current load receiving a bias voltage and coupling the input stage to a first power supply, and a first pair of common mode feedback transistors, coupled to an output of the first current load and configured to limit a current to the first current source. The input stage provides an amplified signal to an additional stage having a structure similar to the input stage, configured to further amplify the amplified signal.

Abstract: Circuits, systems, and methods for generating a variable oscillator output. The circuits generally comprise a capacitor configured to receive first and second currents of a first polarity (e.g., charging currents) and a third current of a second polarity opposite to the first polarity (e.g., a discharge current). The circuit further comprises a first circuit configured to receive a bias input, a second circuit configured to receive a coarse control input, and a third circuit configured to receive a fine control input. The first circuit is further configured to provide the first current in response to the bias input. The second circuit is further configured to provide the second current in response to the coarse control input, such that the second current generally has a magnitude of from zero to a multiple of the magnitude of the first current.

Abstract: A method, algorithm, architecture, circuits, and/or systems for low noise amplification are disclosed. In one embodiment, an amplifier can include an input stage, including a first differential input configured to receive a differential signal, a first current source coupled to the first differential input, a first current load receiving a first bias voltage and coupling the input stage to a first power supply, and a first pair of common mode feedback transistors, coupled to an output of the first current load and configured to limit a current to the first current source. The input stage provides an amplified signal to an additional stage having a structure similar to the input stage, configured to further amplify the amplified signal.

Abstract: A receiver for receiving an amplitude modulated (AM) signal may include a first and a second detector for detecting the maximum and minimum envelope values, respectively, of the received AM signal and an equalizer for periodically equalizing the maximum and minimum envelope values. A method for receiving an AM signal may include unidirectionally increasing a first output signal up to the maximum envelope value, unidirectionally decreasing a second output signal down to the minimum envelope value, and periodically equalizing the first and the second output signals.

Abstract: A method, algorithm, architecture, circuits, and/or systems for using a delay-locked loop (DLL) for phase adjustment in a direct conversion radio receiver are disclosed. In one embodiment, a receiver circuit can include: (i) a voltage-controlled oscillator (VCO) for providing a reference clock; (ii) a delay element that can receive the reference clock and provide a delay adjustment signal; (iii) a first channel for receiving a radio signal and providing a recovered radio signal from the radio signal and the delay adjustment signal, where the first channel includes a first mixer and a first filter; and (iv) a second channel for receiving the radio signal and a phase adjustment signal derived from the delay adjustment signal and for providing a delay control signal to the delay element from the radio signal and the phase adjustment signal, where the second channel includes a second mixer and a second filter.

Abstract: A method, algorithm, architecture, circuits, and/or systems for low noise amplification are disclosed. In one embodiment, an amplifier can include an input stage, including a first differential input configured to receive a differential signal, a first current source coupled to the first differential input, a first current load receiving a first bias voltage and coupling the input stage to a first power supply, and a first pair of common mode feedback transistors, coupled to an output of the first current load and configured to limit a current to the first current source. The input stage provides an amplified signal to an additional stage having a structure similar to the input stage, configured to further amplify the amplified signal.

Abstract: Apparatuses and methods for receiving an amplitude modulated signal in one of two modes depending on the quality of the received signal. In a first mode, the amplitude modulated signal is converted directly to a baseband signal. In a second mode, the amplitude modulated signal is converted to an intermediate frequency signal. The present invention advantageously combines direct conversion and image-rejection heterodyne receiver topologies with a relatively large degree of component reuse and relatively few additional components.

Abstract: A method, algorithm, software, architecture, circuit, and/or system for detecting an idle condition and maintaining a frequency of a clock/data recovery circuit are disclosed. In one embodiment, a method of maintaining a frequency of a clock/data recovery circuit can include the steps of: (i) comparing a difference value from a differential signal with a predetermined threshold (or value); (ii) controlling a variable frequency oscillator (VFO) with a frequency detector when the difference value is less than the threshold for at least a predetermined integration time; and (iii) controlling the VFO with a phase detector receiving the differential signal when the difference value is greater than the threshold. Embodiments of the present invention can advantageously provide a reliable and simplified design approach for clock data recovery (CDR) circuits operable with low power mode transmitters.

Abstract: A frequency synthesizer, for integration in a low voltage digital CMOS process, controls a VCO using a dual loop structure including an analog loop and a digital loop. The digital loop includes an all digital frequency detector, which controls a center frequency of the VCO. The analog loop includes an analog phase detector and charge pump, which add phase coherence to the frequency controlled loop. The analog loop reduces the noise of the digital logic and VCO, and the digital control provides frequency holdover and very low bandwidth. The bandwidth of the digital loop is made smaller than the bandwidth of analog loop, and is preferably 200 times smaller. This parametric difference allows two separate control inputs to the VCO, one from the analog loop and one from the digital loop, with both inputs functioning relatively independently of each other.

Abstract: Circuits and methods for detecting the lock status of a phase locked loop (PLL). The circuit generally comprises (a) a controller configured to produce a control signal in response to a reference clock signal, (b) a counter configured to count pulses of an output signal of the PLL (or a periodic derivative of the output signal) in response to the control signal, and (c) a decoder configured to (i) receive a counter output in response to the control signal, and (ii) produce a lock status output based on the counter output. The method generally comprises the steps of (1) counting pulses of a PLL (or a periodic derivative thereof) in response to a reference clock signal, and (2) indicating a lock status based on the number of counted pulses. The present invention advantageously provides a circuit designer the ability to tune the range of acceptable frequencies by choosing an appropriate reference frequency and adjusting the decoder to produce a positive lock status for a desired range of pulse counts.

Abstract: Apparatuses, circuits, and methods for receiving at least one radio signal in a radio controlled timing apparatus using a single timing source. The present invention advantageously eliminates the need to provide an additional timing source to receive at least one radio signal, and therefore reduces the material cost and eliminates many engineering challenges.

Abstract: A method, circuit, and/or system for controlling an amplitude and/or limiting or reducing the energy consumed by an LC voltage controlled oscillator (LCVCO). In one embodiment, an oscillator can include: (i) a bias circuit that can provide first and second bias signals; (ii) an oscillator core that can provide a periodic signal with a frequency related to the first bias signal and an amplitude, where the oscillator core can also provide a feedback signal; and (iii) a current/amplitude controller that can control the amplitude by dynamically dusting the first bias signal in response to the feedback signal. Embodiments of the present invention can advantageously provide a reliable and simplified design approach for amplitude control and substantial energy reduction in an oscillator, such as an LCVCO circuit or a Colpitts differential oscillator.

Abstract: An differential LNA has first and second input MOS transistors, with differential inputs applied to their respective control gates and differential outputs taken at their respective drains. The gate-to-drain, Cgd, feedback capacitances of the first and second input MOS transistors are neutralized by respective gate-to-source, Cgs, capacitances in the two neutralizing MOS transistors. A first neutralizing MOS transistor has its control gate coupled to the control gate of the first input MOS transistor, its source node coupled to the drain node of the second input MOS transistor, and its drain node coupled to a fixed potential. A second neutralizing MOS transistor has its control gate coupled to the control gate of the second input MOS transistor, its source node coupled to the drain node of the first input MOS transistor, and its drain node coupled to the same fixed potential.

Abstract: Circuits and methods for detecting the lock status of a phase locked loop (PLL). The circuit generally comprises (a) a controller configured to produce a control signal in response to a reference clock signal, (b) a counter configured to count pulses of an output signal of the PLL (or a periodic derivative of the output signal) in response to the control signal, and (c) a decoder configured to (i) receive a counter output in response to the control signal, and (ii) produce a lock status output based on the counter output. The method generally comprises the steps of (1) counting pulses of a PLL (or a periodic derivative thereof) in response to a reference clock signal, and (2) indicating a lock status based on the number of counted pulses. The present invention advantageously provides a circuit designer the ability to tune the range of acceptable frequencies by choosing an appropriate reference frequency and adjusting the decoder to produce a positive lock status for a desired range of pulse counts.

Abstract: A method, algorithm, architecture, circuits, and/or systems for squelch detection in serial communications are disclosed. In one embodiment, a squelch detector can include: (i) a first comparator having first and second inputs configured to receive a differential signal, and a third input configured to receive a signal substantially derived from the differential signal, where the first comparator can provide a comparator output; and (ii) a second comparator that can receive the comparator output and a reference voltage, and may provide a logic level squelch indication. The third input signal may be a common reference signal that is approximately an average voltage of the differential signal, for example. The first comparator may comprise a three-input comparator and the second comparator may comprise a two-input hysteresis comparator, for example. Embodiments of the present invention can advantageously provide a reliable and simplified approach for squelch detection in serial communication applications.

Abstract: A method, circuit, and/or system for controlling an amplitude and/or limiting or reducing the energy consumed by an LC voltage controlled oscillator (LCVCO). In one embodiment, an oscillator can include: (i) a bias circuit that can provide first and second bias signals; (ii) an oscillator core that can provide a periodic signal with a frequency related to the first bias signal and an amplitude, where the oscillator core can also provide a feedback signal; and (iii) a current/amplitude controller that can control the amplitude by dynamically dusting the first bias signal in response to the feedback signal. Embodiments of the present invention can advantageously provide a reliable and simplified design approach for amplitude control and substantial energy reduction in an oscillator, such as an LCVCO circuit or a Colpitts differential oscillator.