Method and apparatus of an input resistance of a passive mixer to broaden the input matching bandwidth of a common source-gate LNA
A cascode common source and common gate LNAs operating at 60 GHz are introduced and described. The cascode common source LNA is simulated to arrive at an optimum ratio of upper device width to the lower device width. The voltage output of the cascode common source LNA is translated into a current to feed and apply energy to the mixer stage. These input current signals apply the energy associated with the current directly into the switched capacitors in the mixer to minimize the overall power dissipation of the system. The LNA is capacitively coupled to the mixer switches in the I and Q mixers and are enabled and disabled by the clocks generated by the quadrature oscillator. These signals are then amplified by a differential amplifier to generate the sum and difference frequency spectra.
1. A receiver comprising:
a Low Noise Amplifier (LNA) coupled to a resonant circuit providing an output signal spectrum;
a capacitor couples the output signal spectrum to a first switched capacitor circuit;
an oscillator clock coupled to the first switched capacitor circuit;
the first switched capacitor circuit presents a first impedance to the resonant circuit; and
the first switched capacitor circuit is configured to mix the oscillator clock and the output signal spectrum into a first mixed signal.
2. The receiver of claim 1 , wherein
the first impedance of the first switched capacitor circuit adjusts a Q of the resonant circuit.
3. The receiver of claim 1 , further comprising:
the output signal spectrum coupled to a second switched capacitor circuit;
an inverse oscillator clock coupled to the second switched capacitor circuit;
the second switched capacitor circuit presents a second impedance to the resonant circuit; and
the second switched capacitor circuit is configured to mix the inverse oscillator clock and the output signal spectrum into a second mixed signal.
4. The receiver of claim 3 , wherein
the first mixed signal and the second mixed signal is a differential intermediate frequency signal.
5. The receiver of claim 4 , further comprising:
a differential amplifier coupled to the differential intermediate frequency signal.
6. The receiver of claim 5 , wherein
the first switched capacitor circuit and the second switched capacitor circuit comprise a first mixer.
7. The receiver of claim 6 , wherein
energy from the resonant circuit is used to power the first mixer.