Abstract: A multiplying analog-to-digital converter is provided. A sample-and-hold unit samples an analog signal, to obtain a sample level. A analog-to-digital converting unit converts the analog signal to a digital signal. A digital-to-analog converting unit converts the digital signal to a recovered signal level. A operating unit provides an output signal according to the difference between the sample level and the recovered signal level. A comparator compares a level of the output signal with an upper threshold level and a lower threshold level, and accordingly provides an indicating signal, wherein the upper and lower threshold levels define a predetermined level range. When the indicating signal indicates that the level of the output signal is outside the predetermined level range, a controller shifts a value of the digital signal and accordingly provides an adjusted digital signal.

Abstract: A multiplying analog-to-digital converter is provided. A sample-and-hold unit samples an analog signal, to obtain a sample level. A analog-to-digital converting unit converts the analog signal to a digital signal. A digital-to-analog converting unit converts the digital signal to a recovered signal level. A operating unit provides an output signal according to the difference between the sample level and the recovered signal level. A comparator compares a level of the output signal with an upper threshold level and a lower threshold level, and accordingly provides an indicating signal, wherein the upper and lower threshold levels define a predetermined level range. When the indicating signal indicates that the level of the output signal is outside the predetermined level range, a controller shifts a value of the digital signal and accordingly provides an adjusted digital signal.

Abstract: An RF signal receiving apparatus includes a first poly-phase filter, a second poly-phase filter, a first frequency-mixer module, a switch and a low-pass filter module. The first poly-phase filter receives an RF input signal and produces a filtered RF signal according to the received RF input signal. The first frequency-mixer module conducts frequency-mixing operation on a reduced-frequency signal and the filtered RF signal to produce a plurality of reduced-frequency RF signals. The switch receives and transmits the reduced-frequency RF input signal to a first channel or a second channel according to a selection signal. The second poly-phase filter receives the reduced-frequency RF signal transmitted by the second channel and filters the received signal.

Abstract: An RF signal receiving apparatus includes a first poly-phase filter, a second poly-phase filter, a first frequency-mixer module, a switch and a low-pass filter module. The first poly-phase filter receives an RF input signal and produces a filtered RF signal according to the received RF input signal. The first frequency-mixer module conducts frequency-mixing operation on a reduced-frequency signal and the filtered RF signal to produce a plurality of reduced-frequency RF signals. The switch receives and transmits the reduced-frequency RF input signal to a first channel or a second channel according to a selection signal. The second poly-phase filter receives the reduced-frequency RF signal transmitted by the second channel and filters the received signal.

Abstract: The present invention relates to a differential feedback amplifier circuit with cross coupled capacitors. Wherein, the first and second input terminals of a source follower are respectively coupled to the first and second output terminals of a differential amplifier, and a resistor is respectively coupled between the first output terminal of the source follower and the first input terminal of the differential amplifier and between the second output terminal of the source follower and the second input terminal of the differential amplifier in order to form a feedback loop. In addition, a capacitor is respectively coupled between the first end current source gate of the source follower and the second input terminal of the source follower and between the second end current source gate of the source follower and the first input terminal of the source follower, so as to improve the circuit gain and bandwidth.

Abstract: The present invention relates to a differential feedback amplifier circuit with cross coupled capacitors. Wherein, the first and second input terminals of a source follower are respectively coupled to the first and second output terminals of a differential amplifier, and a resistor is respectively coupled between the first output terminal of the source follower and the first input terminal of the differential amplifier and between the second output terminal of the source follower and the second input terminal of the differential amplifier in order to form a feedback loop. In addition, a capacitor is respectively coupled between the first end current source gate of the source follower and the second input terminal of the source follower and between the second end current source gate of the source follower and the first input terminal of the source follower, so as to improve the circuit gain and bandwidth.

Abstract: An integrated television tuner, which enhances image rejection by employing a filter device between the first mixing and the second mixing operations in a dual-conversion architecture. Signal selectivity is improved and linearity requirement on following stages is reduced.

Abstract: A first local oscillator operating at a first frequency provides a first reference signal and a second reference signal. The second reference signal is the first reference signal phase shifted by 90 degrees. A first harmonic mixer has inputs coupled to a received RF signal, the first reference signal, and the second reference signal. A band-pass filter is coupled to an output of the first harmonic mixer. A second local oscillator operates at a second frequency and provides a third, a fourth, a fifth, and a sixth reference signal, which are phase shifted by 0 degrees, 45 degrees, 90 degrees, and 135 degrees, respectively. A second harmonic mixer has inputs coupled to an output of the band-pass filter, the third reference signal, and the fifth reference signal. A third harmonic mixer has inputs coupled to the output of the band-pass filter, the fourth reference signal, and the sixth reference signal.

Abstract: A television (TV) tuner includes a first mixer having an input terminal coupled to a received RF signal for producing an intermediate frequency signal, a notch filter having an input terminal coupled to the intermediate frequency signal for removing a first range of signals centered at a first center frequency in the intermediate frequency signal, a band-pass filter having an input terminal coupled to the intermediate frequency signal for passing a second range of signals centered at a second center frequency in the intermediate frequency signal, and a second mixer having inputs coupled to a filtered intermediate frequency signal for producing a first output signal. The filtered intermediate frequency signal is received from an output of the notch filter and the band-pass filter.

Abstract: A television receiver includes a digital TV preamp for amplifying a received RF signal within a first frequency range, a satellite TV preamp for amplifying the received RF signal within a second frequency range, a first mixer having inputs coupled to the output of either the digital or satellite TV preamp according to a mode selection signal, a digital TV band-pass filter for filtering the output of the first mixer centered at a first center frequency being selectively coupled to the output of the first mixer according to the mode selection signal, a satellite TV band-pass filter for filtering the output of the first mixer centered at a second center frequency being selectively coupled to the output of the first mixer according to the mode selection signal, and a second mixer stage having inputs coupled to the output of the digital TV filter stage and the satellite TV filter stage.

Abstract: An injection-locked frequency divider includes a selecting module for generating a control signal; a biasing module coupled to the selecting module, for receiving an original signal and generating a biasing signal according to the control signal; and an oscillating module coupled to the biasing module, for receiving the biasing signal to generate a target signal. A ratio exists between the frequency of the target signal and the frequency of the original signal.

Abstract: A television (TV) tuner includes a first mixer for mixing a received RF signal with a first local oscillator signal to produce an intermediate frequency signal, a second mixer for mixing the intermediate frequency signal with a second local oscillator signal for producing an in-phase baseband output signal, a third mixer for mixing the intermediate frequency signal with a third local oscillator signal for producing a quadrature-phase baseband output signal, the third local oscillator signal being the second local oscillator signal phase delayed, and a single phase locked loop (PLL) coupled to the first mixer and the second mixer unit for generating the first local oscillator signal and the second local oscillator signal according to a selected channel in the received RF signal.

Abstract: A linear-in-decibel variable gain amplifier used for receiving an input voltage and generating an output voltage according to a first controlling voltage and a second controlling voltage. A voltage gain, that is, the ratio between the output voltage and the input voltage, has a denominator that is a pure exponential function, and the value of the pure exponential function is determined by the first controlling voltage and second controlling voltage.

Abstract: A linear decibel-scale variable gain amplifier includes an amplifying stage for generating an output voltage according to a differential input voltage, and a gain-controlling stage for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the linear decibel-scale variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage. The value of the voltage gain is unaffected by changes of the thermal voltage.

Abstract: A variable gain amplifier having a linear decibel-scale gain comprises an amplifying stage for generating an output voltage according to a differential input voltage, and a gain-controlling stage for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage.

Abstract: A passive harmonic switch mixer is shown that is immune to self mixing of the local oscillator greatly reducing leakage noise, pulling noise, and flicker noise when used in a direct conversion receiver or direct conversion transmitter circuit. The passive harmonic switch mixermixes an input signal received on an input port with an in-phase oscillator signal and a quadrature-phase oscillator signal and outputs an output signal on an output port. Because the quadrature-phase oscillator signal is the in-phase oscillator signal phase shifted by 90 °, the passive harmonic switch mixer operates with a local oscillator running at half the frequency of the carrier frequency of an RF signal. Additionally, because the passive harmonic switch mixer has no active components, the DC current passing through each switch device is reduced and the associated flicker noise of the mixer is also greatly reduced.

Abstract: An injection-locked frequency divider includes a selecting module for generating a control signal; a biasing module coupled to the selecting module, for receiving an original signal and generating a biasing signal according to the control signal; and an oscillating module coupled to the biasing module, for receiving the biasing signal to generate a target signal. A ratio exists between the frequency of the target signal and the frequency of the original signal.

Abstract: A television (TV) tuner includes a first mixer having an input terminal coupled to a received RF signal for producing an intermediate frequency signal, a notch filter having an input terminal coupled to the intermediate frequency signal for removing a first range of signals centered at a first center frequency in the intermediate frequency signal, a band-pass filter having an input terminal coupled to the intermediate frequency signal for passing a second range of signals centered at a second center frequency in the intermediate frequency signal, and a second mixer having inputs coupled to a filtered intermediate frequency signal for producing a first output signal. The filtered intermediate frequency signal is received from an output of the notch filter and the band-pass filter.

Abstract: A linear decibel-scale variable gain amplifier includes an amplifying stage for generating an output voltage according to a differential input voltage, and a gain-controlling stage for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the linear decibel-scale variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage. The value of the voltage gain is unaffected by changes of the thermal voltage.

Abstract: A variable gain amplifier having a linear decibel-scale gain comprises an amplifying stage for generating an output voltage according to a differential input voltage, and a gain-controlling stage for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage.