Patent ID: 9325332
Filing Date: 2016-04-26
CPC Classification: H03B,H03H,H03J,H03K,H03L

Claim Text:
1. An apparatus comprising: a digitally controlled circuit having a variable capacitance, wherein the digitally controlled circuit comprises a plurality of gain elements, the plurality of gain elements comprising one or more positive voltage-to-frequency gain elements and one or more negative voltage-to-frequency gain elements; a controller configured to adjust a magnitude of the variable capacitance of the digitally controlled circuit; a digital-to-analog converter providing a digital-to-analog control voltage responsive to control codes supplied by the controller; and a plurality of switches configured to select one of the digital-to-analog control voltage, a fixed high voltage and a fixed low voltage to connect to corresponding ones of the plurality of gain elements responsive to corresponding control signals from the controller; wherein the controller is configured to adjust the magnitude of the capacitance by adjusting the gain provided by respective ones of the gain elements in an alternating sequence of the positive voltage-to-frequency gain elements and the negative voltage-to-frequency gain elements; wherein the controller is configured to adjust the control signals such that one of the plurality of gain elements is supplied with the digital-to-analog control voltage while remaining ones of the plurality of gain elements are supplied with the fixed high voltage or the fixed low voltage; and wherein the digital-to-analog converter comprises a transfer function such that at least a top two control codes produce a same maximum voltage and at least a bottom two control codes produce a same minimum voltage.