Slew-rate limited voltage controlled oscillator clamp circuit

Abstract From the Canadian patent

A clamp circuit for use in a clock circuit having a phase-lock loop, the phase-lock loop including a phase detector, a loop filter, and a voltage-controlled oscillator, the clamping circuit connected between the loop filter and the voltage-controlled oscillator. The clamping circuit selectively provides, under the control of a clamping signal either a path for the loop through the clamping circuit or clamping the input of the voltage-controlled oscillator to varying potential. The varying potential is provided by a resistor capacitor network. When the loop is closed the capacitor is charged to an average of the loop control voltage for the oscillator. In response to the clamping signal the …