Differential voltage follower
First Claim
1. 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.
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Accused Products
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.
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Citations
6 Claims
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1. A differential voltage follower, comprising:
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(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. - View Dependent Claims (2, 3, 4, 5)
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6. A differential voltage follower, comprising:
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(a) first and second input nodes; (b) first and second field effect transistors with a gate of said first transistor coupled to said first node and a gate of said second transistor coupled to said second node; (c) third, fourth, fifth, and sixth bipolar transistors cross-coupled with the collectors of said third and sixth bipolars connected to the source of said first field effect transistor and the collectors of said fourth and fifth bipolars connected to the source of said second field effect transistor, said fourth bipolar mirroring the collector current of said third bipolar, and said sixth bipolar mirroring the collector current of said fifth bipolar, whereby the drain current of said first and second field effect transistors is each split between said mirroring bipolars; and (d) first and second output nodes, said first output node connected to the emitter of said third bipolar and said second output node connected to the emitter of said fifth bipolar.
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Specification