Abstract: Variable frequency oscillators allowing wide tuning range and low phase noise is disclosed. In an illustrative embodiment, a first transistor has a first terminal (e.g. collector) connected to a reference voltage, and a second terminal (e.g. emitter) connected to a first terminal of a first current source and to ground. The first transistor further has a third terminal connected to a first inductor and to a first capacitor connected to the emitter of the first transistor and also to a second capacitor connected to ground. A second transistor is similarly constructed. In order to achieve a variable frequency oscillation between the emitters of the two transistors, a variable tank capacitor is connected between the inductors, forming a circuit connecting in series all passive components composing the LC tank, masking most of parasitic capacitances.

Abstract: A multiloop PLL circuit comprising: a first PLL loop comprising a first VCO, a first phase detector having a first input receiving a reference frequency (Fref) and a second input receiving the output of a first programmable divider, which input receives the signal generated by the first VCO and a first loop filter connected between said first phase detector and said first VCO; at least one auxiliary PLL loop comprising a second VCO, a second phase detector, a second (R1) and a third (N1) programmable dividers, and a second loop filter a main loop for generating a desired output frequency Fout comprising a third VCO, a third phase detector, a fourth (Rn) and a fifth (Nn) programmable divider, a main loop filter and a mixer additional possible auxiliary PLL loop each comprising a forth VCO, a forth phase detector, a sixth (Ri) and a seventh (Ni) programmable divider, a third auxiliary loop filter and a mixer whereby the desired output frequency Fout is generated in accordance with the relation: Fout=(N1/R1+

Abstract: A variable frequency oscillator comprising a first transistor (10) and a second transistor (20); wherein the first transistor (10) has a first terminal—collector—which is connected to a reference voltage, and a second terminal—emitter—which is connected to a first terminal of a first current source (13), which second terminal is connected to ground, and a third terminal—base—connected to a first terminal of a first inductor (14) and to a top terminal of a first capacitor (11), wherein the first capacitor (11) has a bottom terminal which is connected to the second terminal—emitter—of the first transistor (10) but also to a top terminal of a second capacitor (12) having a bottom terminal being connected to ground; wherein the second transistor (20) has a first terminal—collector—which is connected to a reference voltage, and a second terminal—emitter—which is connected to a first terminal of a second current source (23), which second terminal is connected to ground, and a third terminal—base—connected to a f

Abstract: A multiloop PLL circuit comprising: a first PLL loop comprising a first VCO, a first phase detector having a first input receiving a reference frequency (Fref) and a second input receiving the output of a first programmable divider, which input receives the signal generated by the first VCO and a first loop filter connected between said first phase detector and said first VCO; at least one auxiliary PLL loop comprising a second VCO, a second phase detector, a second (R1) and a third (N1) programmable dividers, and a second loop filter a main loop for generating a desired output frequency Fout comprising a third VCO, a third phase detector, a fourth (Rn) and a fifth (Nn) programmable divider, a main loop filter and a mixer additional possible auxiliary PLL loop each comprising a forth VCO, a forth phase detector, a sixth (Ri) and a seventh (Ni) programmable divider, a third auxiliary loop filter and a mixer whereby the desired output frequency Fout is generated in accordance with the relation: Fout=(N

Abstract: A tunable multiple frequency source system employing offset signal phasing includes a first frequency source, a phase delay element, and a second frequency source configured to operate concurrently with the first frequency source. The first frequency source includes an input coupled to receive a reference input signal and an output for providing a first frequency source signal. The phase delay includes an input coupled to receive the input reference signal, and an output, the phase delay element operable to apply a predefined phase delay to the input reference signal to produce a phase-delayed input signal. The second frequency source includes an input coupled to receive the phase-delayed input signal and an output for providing a second frequency source signal.

Abstract: A multiple frequency source system includes at least one frequency source tunable to a predefined target frequency, and at least one additional frequency source operable to generate a second signal at a frequency which is either higher or lower than the target frequency. A method for tuning the tunable frequency source to the target frequency during concurrent generation of the second signal includes (i) controlling the tunable frequency source to tune to at least one frequency point frequency lower than the target frequency, and thereafter controlling the oscillator to tune to the target frequency, when the second signal is higher in frequency than the target frequency, or (ii) controlling the tunable frequency source to tune to at least one frequency point higher than the target frequency, and thereafter controlling the tunable frequency source to tune to the target frequency, when the second signal is lower in frequency than the target frequency.

Abstract: A method for mitigating phase pulling in multiple frequency source system includes generating a first signal, the first signal referred to as an existing signal operating at an existing frequency point, the existing signal having a predefined pulling bandwidth around the existing frequency point. A request is received to generate a prospective signal at a prospective frequency point which is within the predefined pulling bandwidth of the existing signal. The prospective frequency is removed from within the predefined pulling bandwidth, and the prospective and existing signals are generated at the corresponding frequency points.

Abstract: A method for mitigating phase pulling in multiple frequency source system includes generating a first signal, the first signal referred to as an existing signal operating at an existing frequency point, the existing signal having a predefined pulling bandwidth around the existing frequency point. A request is received to generate a prospective signal at a prospective frequency point which is within the predefined pulling bandwidth of the existing signal. The prospective frequency is removed from within the predefined pulling bandwidth, and the prospective and existing signals are generated at the corresponding frequency points.

Abstract: A multiple frequency source system includes at least one frequency source tunable to a predefined target frequency, and at least one additional frequency source operable to generate a second signal at a frequency which is either higher or lower than the target frequency. A method for tuning the tunable frequency source to the target frequency during concurrent generation of the second signal includes (i) controlling the tunable frequency source to tune to at least one frequency point frequency lower than the target frequency, and thereafter controlling the oscillator to tune to the target frequency, when the second signal is higher in frequency than the target frequency, or (ii) controlling the tunable frequency source to tune to at least one frequency point higher than the target frequency, and thereafter controlling the tunable frequency source to tune to the target frequency, when the second signal is lower in frequency than the target frequency.

Abstract: A tunable multiple frequency source system employing offset signal phasing includes a first frequency source, a phase delay element, and a second frequency source configured to operate concurrently with the first frequency source. The first frequency source includes an input coupled to receive a reference input signal and an output for providing a first frequency source signal. The phase delay includes an input coupled to receive the input reference signal, and an output, the phase delay element operable to apply a predefined phase delay to the input reference signal to produce a phase-delayed input signal. The second frequency source includes an input coupled to receive the phase-delayed input signal and an output for providing a second frequency source signal.

Abstract: A low noise amplifier circuit (10) includes an attenuator (12) for receiving a calibration signal and generating an attenuated calibration signal. A low noise amplifier (14) amplifies the attenuated calibration signal in calibration mode or amplifies a functional signal in functional mode. In calibration mode, a envelope detector/comparator (16) compares the calibration signal with the output of the low noise amplifier and generates a compensation signal indicating a deviation between the two signals. The gain of the low noise amplifier is adjusted responsive to the compensation signal.

Abstract: A gain control system in a Direct Conversion Receiver or similar receiver, includes an automatic gain control circuit which determines whether a low noise amplifier, which amplifies signals from an antenna prior to mixing with signals from a local oscillator, should be set to a high gain or a low gain. The output of the mixer is analyzed by a blocker detect circuit to determine whether a blocker signal is present. Based on the presence of a blocker signal and the power level of the useful signal, the gain of the low noise amplifier may be reduced from the high gain to an intermediate gain in order to reduce self mixing between the radio frequency and local oscillator ports of the mixer, which may lead to dynamic DC offsets.

Abstract: A transfer function generator provides the ability to provide a non-linear response in a feedback loop to compensate for non-linearities introduced elsewhere in the system. The transfer function generator includes a non-linear function generator configured to provide an output current that is a non-linear function of an input signal representing an error to be corrected. The transfer function generator can also include a linear function generator configure to provide a linear output current as a function of an input current representing the error corrected. Tuning devices can be provided to adjust the turn-on level of the non-linear function generator and the output level of the linear function generator to allow the transfer function generator flexibility in implementation.