Patent ID: 6316977
Filing Date: 2001-11-13
Classification: H03L

Abstract:
A low charge-injection charge pump, comprising:a first FET current source, coupled to a charge summing node, for supplying charge to the charge summing node;a first FET switch, switchably coupling the first FET current source to a first reference voltage supply, the first FET switch being controlled to supply current to the first FET current source in response to assertion of a first input signal;a second FET current source, coupled to a charge summing node, for removing the charge from the charge summing node;a second FET switch, switchably coupling the second FET current source to a second reference voltage supply, the second FET switch being controlled to sink current from the second FET current source in response to assertion of a second input signal, wherein an output voltage of the charge summing node increases in response to the assertion of the first input signal and decreases in response to the assertion of the second input signal;a first biasing circuit that in response to deassertion of the first input signal biases the first FET current source so that the first FET current source does not conduct current; anda second biasing circuit that in response to deassertion of the second input signal biases the second FET current source so that the second FET current source does not conduct current.