Split cascode circuits and related communication receiver architectures

Patent metadata

Field	Value
Publication number	US-10312873-B2
Application number	US-201815863473-A
Country	US
Kind code	B2
Filing date	Jan 5, 2018
Priority date	Mar 18, 2016
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

Split cascode circuits include multiple cascode paths coupled between voltage supply rails. Each cascode path includes a pair of controllable switches. A feedback path is provided for at least one of the cascode circuit paths. An active load circuit may also have a split cascode structure. Multiple-stage circuits, for implementation in Trans-Impedance Amplifiers (TIAs) or analog Receive Front-End modules (RXFEs), for example, include multiple stages of split cascode circuits.

First claim

We claim:

1. An apparatus comprising:
an input to receive an input signal;
a first controllable switch coupled to a first voltage supply rail and having a first control terminal;
a second controllable switch coupled to a second voltage supply rail and having a second control terminal coupled to the first control terminal, the second voltage supply rail being different from the first voltage supply rail;
a split cascode structure comprising multiple cascode circuit paths coupled between the first controllable switch and the second controllable switch, each of the cascode circuit paths comprising a respective pair of controllable switches;
a feedback path coupled to the first and second control terminals and to a feedback point between the pair of controllable switches of one of the cascode circuit paths;
a third controllable switch coupled to the first voltage supply rail and having a control terminal coupled to a load;
a fourth controllable switch coupled to the second voltage supply rail and having a control terminal coupled to the load;
a cascode circuit path coupled between the third controllable switch and the fourth controllable switch, and comprising a pair of controllable switches; and
a feedback path coupled to the load and to a feedback point between the pair of controllable switches of the cascode circuit path,
wherein a load point between the pair of controllable switches of the cascode circuit path is coupled to an output point in one of the multiple cascode circuit paths.

2. The apparatus of claim 1 , further comprising:
a respective feedback path coupled to the first and second control terminals and to a feedback point between the pair of controllable switch elements of each of the cascode circuit paths other than the one of the cascode circuit paths.

3. The apparatus of claim 2 , wherein the cascode circuit paths comprise more than two cascode circuit paths, and wherein the respective feedback paths comprise segments of a cascaded feedback path, the cascaded feedback path segments comprising a first feedback path segment coupled to the first and second control terminals and to a first feedback point between the pair of controllable switches of a first cascode circuit path of the multiple cascode circuit paths and one or more respective further feedback path segments between feedback points in adjacent cascode circuit paths of the multiple cascode circuit paths.

4. The apparatus of claim 1 , further comprising:
an input, coupled to the first and second control terminals.

5. The apparatus of claim 1 , further comprising:
a pair of outputs coupled to respective output points between the pairs of controllable switches of two of the cascode circuit paths;
an input, coupled to an input point between the pair of controllable switches of the one of the cascode circuit paths.

6. The apparatus of claim 1 , further comprising:
a further cascode circuit path coupled between the third controllable switch and the fourth controllable switch, and comprising a pair of controllable switches; and
a further feedback path coupled to the load and to a further feedback point between the pair of controllable switches of the further cascode circuit path.

7. The apparatus of claim 1 , wherein the pair of controllable switches of the one of the cascode circuit paths comprises:
a first set of multiple controllable switches having respective first current carrying terminals coupled to the first controllable switch and respective second current carrying terminals coupled together; and
a second set of multiple controllable switches having respective first current carrying terminals coupled together and coupled to the second current carrying terminals of the controllable switches of the first set of multiple controllable switches, and respective second current carrying terminals coupled to the second controllable switch.

8. The apparatus of claim 1 , further comprising:
an amplifier coupled to receive a gain control signal based upon which the pair of controllable switches of the one of the cascode circuit paths are controlled, and a reference signal; and
a capacitor coupling an output of the amplifier to the input.

9. An apparatus comprising:
an input to receive an input signal;
a first controllable switch coupled to a first voltage supply rail and having a first control terminal;
a second controllable switch coupled to a second voltage supply rail and having a second control terminal coupled to the first control terminal, the second voltage supply rail being different from the first voltage supply rail;
a split cascode structure comprising multiple cascode circuit paths coupled between the first controllable switch and the second controllable switch, each of the cascode circuit paths comprising a respective pair of controllable switches;
a feedback path coupled to the first and second control terminals and to a feedback point between the pair of controllable switches of one of the cascode circuit paths; and
a gain controller, the gain controller comprising
a split cascode stage comprising:
a third controllable switch coupled to the first voltage supply rail and having a control terminal;
a fourth controllable switch coupled to the second voltage supply rail and having a control terminal coupled to the control terminal of the third controllable switch;
multiple cascode circuit paths coupled between the third controllable switch and the fourth controllable switch, each of the multiple cascode circuit paths of the split cascode stage comprising a pair of controllable switches;
respective resistors coupling together the control terminals of the controllable switches of the cascode circuit paths in the split cascode stage that are coupled to the third controllable switch and coupling together the control terminals of the controllable switches of the cascode circuit paths in the split cascode stage that are coupled to the fourth controllable switch; and
feedback paths coupled to the control terminals of the third and fourth controllable switches and to respective feedback points between the pairs of controllable switches of the cascode circuit paths in the split cascode stage; and
a current mirror and amplifier stage comprising:
a variable current source;
a current mirror coupled to the variable current source and to a control terminal of a controllable switch, of the pair of controllable switches of one of the cascode circuit paths in the split cascode stage, which is coupled to the fourth controllable switch; and
an amplifier coupled to the current mirror, the amplifier having an output coupled to a control terminal of a controllable switch, of the pair of controllable switches of the one of the cascode circuit paths in the split cascode stage, which is coupled to the third controllable switch, the amplifier further having inputs coupled across one of the feedback paths that is coupled to the control terminals of the third and fourth controllable switches and to one of the respective feedback points between the pairs of controllable switches of the cascode circuit paths in the split cascode stage,

wherein gain control signals to control the pair of controllable switches of the one of the cascode circuit paths in the split cascode stage are generated at the control terminals of the pair of controllable switches of the one of the cascode circuit paths in the split cascode stage.

10. An apparatus, comprising:
an input to receive an input signal;
a first controllable switch coupled to a first voltage supply rail and having a first control terminal;
a second controllable switch coupled to a second voltage supply rail and having a second control terminal coupled to the first control termin

Assignees

• Inphi Corp

Inventors

• Pera Florin
• Dallaire Stephane
• Wall Brian

Classifications

• H03F1/08

  Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements (wide-band amplifiers with inter-stage coupling networks incorporating these impedances H03F1/42) · CPC title

• H03F2200/411

  the output amplifying stage of an amplifier comprising two power stages · CPC title

• H03G1/0088

  using discontinuously variable devices, e.g. switch-operated · CPC title

• H04Q2011/0035

  using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical · CPC title

• H04B10/6931

  Automatic gain control of the preamplifier · CPC title