US 5,382,916 A · Differential voltage follower

Abstract

A two-step analog-to-digital converter and BiCMOS fabrication method. The fabrication method provides pseudosubstrate isolation of digital CMOS devices from the analog devices. The converter uses NPN current switching in a flash analog-to-digital converter and in a digital-to-analog converter for low noise operation. CMOS digital error correction and BiCMOS output drivers provide high packing density plus large output load handling. Timing control aggregates switching events and puts them into intervals when noise sensitive operations are inactive. The fabrication method uses a thin epitaxial layer with limited thermal processing to provide NPN and PNP devices with large breakdown and Early voltages. Laser trimmed resistors provide small long term drift due to dopant stabilization in underlying BPSG and low hydrogen nitride passivation.

Claims6

Dependent claims

A differential voltage follower, comprising:

(a) a first input node connected to a first load;
(b) a second input node connected to a second load, said second load matched to said first load;
(c) a first follower with input connected to said first input node and with output connected to a control input of both said first and second loads;
(d) a second follower with input connected to said second input node and with output connected to an output node;
(e) wherein said first follower includes a first current mirror and said second follower includes a second current mirror, said first and second current mirrors cross-coupled to tie the currents through said followers.

2 more elements

Dependencies are inferred from the claim text.

Differential voltage follower

Life of this patent

Differential voltage follower

Life of this patent

Abstract

Claims6