Abstract: The VCO of a synthesizer operates with a coarse tuning and a fine tuning. During the coarse tuning, a binary search method is used to match the VCO frequency to one of a finite number of discrete reference frequencies. The coarse tuning operates without frequency division and phase comparison in a closed feedback loop, thereby speeding up the settling time and increasing the lock-in range. The fine tuning operates as a conventional analog PLL.

Abstract: A MOSFET operating as a mixer has its drain biased at the knee of the ID vs VDS characteristic. A local oscillator voltage is applied to the gate and a RF signal voltage is applied to the drain through a singled-ended source follower. The nonlinear curvature at the knee produces a beat frequency current. This mixer requires less supply voltage, and results in more conversion gain and less feed-through of the RF input signal than the Gilbert multiplier. Conversely, the RF voltage can be applied to the gate and the local oscillator voltage can be applied to the drain.

Abstract: During transient operation of a voltage regulator, the gate of p-channel MOS pass transistor may be pulled down during the transient period to cause excessive surge current. The surge current is limited by using the pass transistor as a current mirror during the transient period. After the transient period, the pass transistor resumes its role as an element together with a differential amplifier and a reference voltage in a feedback loop to regulate the output voltage.

Abstract: The frequency of oscillation of two cross-coupled CMOS inverters with a parallel LC tank connected between the two drains can be varied by a control voltage which varies the capacitance value of the tank circuit. The gate-to-source capacitance is used as the variable capacitance. The gate-to-source capacitance is varied by changing the dc gate voltage, which can be effected by either changing the dc current through the inverters or by varying the dc voltage across the inverters. The control voltage may also be made to vary with temperature such that the free running frequency of the oscillator is held constant with varying temperature.