To apply a desired voltage at a node driving a load impedance, a voltage source providing the desired voltage is connected to the node. In addition, a current source supplying an amount of current that would be drawn by the impedance if the voltage source alone were connected across the impedance. As a result, the voltage source may be freed substantially from supplying current, which may be advantageously used in several situations. For example, the approach can be used to connect a voltage sou...

The comparator input stage uses low voltage transistors 20 and 21 as the input pair. They have a small threshold voltage, and hence support a low common mode. The circuit includes a current sink 22 coupled to the input pair 20 and 21; a first resistor 33 coupled between a first branch of the input pair and a voltage node V24; a second resistor 36 coupled between a second branch of the input pair and the voltage node V24; a first transistor 23 coupled to the voltage node V24; a second transistor ...

An analog circuit 20 includes an amplifier 30 with a positive input node, a negative input node, a positive output node and a negative output node. A first capacitor 32 is coupled between the negative input node and an analog signal node. A second capacitor 34 is coupled between the positive input node and a reference voltage node. In addition, a third capacitor 36 is coupled between the positive input node and the negative output node and a fourth capacitor 38 is coupled between the negative in...

Providing a substantially constant reference voltage to a component from a reference buffer connected by a path. The load that would be offered to the reference buffer in desired durations is estimated, and a dummy load is added to the path such that the aggregate load on the path is approximately constant. In case of the stages of an ADC, the sub-code generated by each stage during a sampling phase is used to estimate the load that would be offered, and the dummy load is added in the hold phase...

An aspect of the present invention reduces the effect of any noise present along with an input signal when sampling the input signal by charging each of several parallel connected capacitors for different time durations with at least some non-overlap. In an embodiment, such an approach is used in a switched capacitor amplifier circuit of an ADC. The capacitors in that embodiment start charging at the same time instance, but stop charging at different time instances due to the design of associate...

A bandwidth limited sampling circuit of high linearity may be implemented by using a first circuit portion to limit the bandwidth of the input signals, and using a second circuit portion to sample the bandwidth limited input signal. The first circuit portion and the second circuit portion may be implemented using separate components. In an alternative embodiment, bandwidth limiting is implemented by taking a difference of a sampled input signal from a sampled high frequency components of the inp...

A low-noise output buffer for a digital signal is based on an analog amplifier having bandwidth greater than the switching rate of the digital logic signal. A converter circuit converts the digital logic signal to a ramp signal provided as an input to the analog amplifier. The ramp signal has a slope determined by a bias current and an input capacitance of the analog amplifier. The bias current is generated by a bias circuit such that the bias current varies as the input capacitance of the analo...

An ADC implemented according to an aspect of the present invention contains a non-zero bit stage followed by a zero-bit stage. The non-zero bit stage generates a sub-code, which is used in generating a digital code corresponding to an input analog signal, and the zero-bit stage does not provide any such sub-codes. Such a feature may be attained by using a gain amplifier provided according to another aspect of the present invention. The gain amplifier contains a main-amplifier which operates as a...

An amplification circuit sharing a main amplifier in two gain stages while minimizing power consumption. A Miller Compensated Amplifier contains the main amplifier and a pre-amplifier, with the output of the pre-amplifier being connected to the input of the main amplifier. In a first gain stage, the two amplifiers together amplify an input signal. The main amplifier is then disconnected from the pre-amplifier in a second gain stage to further amplify the amplified signal of the first gain stage....

An aspect of the present invention reduces droop in the reference signal provided to ADCs. A compensation resistor of appropriate resistance value is provided in the path of the reference signal to minimize the droop.