US 6,150,968 AGranted

Trimming circuitry for pipeline A/D converter

AssigneeTexas Instruments Incorporated

InventorsChing-yuh Tsay, Eric G. Soenen

Life of this patent

Estimating the term…

Loading patent…

Abstract

A trimming circuit for a gain stage in a pipeline analog-to-digital converter includes an amplification stage (30) having associated therewith on one input thereof a coupling capacitor (38). In parallel with the coupling capacitor is provided a trimming network. The trimming network includes a series configuration of a coupling capacitor and a plurality of trimming capacitors, which trimming capacitors can be disposed in parallel with each other. Each of the trimming capacitors has associated therewith a switch which allows them to be selectively disposed in series with a coupling capacitor (42) and in parallel with each other. This trimming network is connected in parallel with the sampling capacitor (38). The input to the amplifier is isolated from the trimming network with a buffer (62) which is operable to isolate the impedance of the trimming capacitors from the input and from preceding stages.

Claims12

Dependent claims

An input gain stage for amplifying an input signal received on a signal input, comprising:

an amplifier having an input and an output;
an input capacitor having one plate thereof connected to the signal input and the other plate thereof connected to the input of said amplifier;
a feedback capacitor having one plate thereof connected to the input of said amplifier and the other plate thereof connected to the output of said amplifier;
a variable trimming capacitance network having a first side and a second side, with said first side connected to the input of said amplifier, said variable trimming capacitance network having a variable capacitance value;
and
a buffer connected between said signal input and said second side of said trimming capacitance network for isolating the input capacitance on said second side of said trimming capacitance network from said signal input and any preceding gain stages attached thereto;
the combination of said buffer and said trimming capacitance network defining a parallel capacitance which is disposed in parallel with said input capacitor such that the combination of said input capacitor, said trimming capacitance network and said buffer constituting an effective input capacitance, and wherein the ratio of said effective input capacitance to said feedback capacitor defines the gain of said amplifier.

4 more elements

Dependencies are inferred from the claim text.