Multi-cascode amplifier bias techniques
First Claim
1. An apparatus comprising:
- multi-cascode bias transistors comprising first and second cascode bias transistors and an input bias transistor, the input bias transistor comprising a drain coupled to the source of the first cascode bias transistor; and
first and second impedance networks coupled to a first supply voltage for generating bias voltages for the first and second cascode bias transistors, respectively, at least one of the first and second impedance networks comprising a configurable impedance for adjusting at least one bias voltage for the first and second cascode bias transistors;
wherein the input bias transistor is biased to a gate voltage determined by a reference current through a transistor that is a replica of the input bias transistor.
1 Assignment
0 Petitions
Accused Products
Abstract
Techniques for generating bias voltages for a multi-cascode amplifier. In an aspect, a multi-cascode bias network is provided, each transistor in the bias network being a replica of a corresponding transistor in the multi-cascode amplifier, enabling accurate biasing of the transistors in the multi-cascode amplifier. In another aspect, a voltage supply for the multi-cascode amplifier is provided separately from a voltage supply for the replica bias network, to advantageously decouple variations in the amplifier voltage supply from the bias network voltage supply. In yet another aspect, the bias voltages of transistors in the multi-cascode amplifier may be configured by adjusting the impedance of resistive voltage dividers coupled to the transistor gate biases. As the gain of the amplifier depends on the bias voltages of the cascode amplifiers, the gain of the amplifier may be adjusted in this manner without introducing a variable gain element directly in the amplifier signal path.
109 Citations
19 Claims
-
1. An apparatus comprising:
-
multi-cascode bias transistors comprising first and second cascode bias transistors and an input bias transistor, the input bias transistor comprising a drain coupled to the source of the first cascode bias transistor; and first and second impedance networks coupled to a first supply voltage for generating bias voltages for the first and second cascode bias transistors, respectively, at least one of the first and second impedance networks comprising a configurable impedance for adjusting at least one bias voltage for the first and second cascode bias transistors; wherein the input bias transistor is biased to a gate voltage determined by a reference current through a transistor that is a replica of the input bias transistor. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. An apparatus comprising:
-
multi-cascode bias transistors comprising first and second cascode bias transistors and an input bias transistor, the input bias transistor comprising a drain coupled to the source of the first cascode bias transistor; and a multi-cascode amplifier comprising; a first cascode transistor comprising a gate coupled to the bias voltage of the first cascode bias transistor; and a second cascode transistor comprising a gate coupled to the bias voltage of the second cascode bias transistor; and an input transistor coupled to the source of the first cascode transistor, the input transistor comprising a gate coupled to the gate voltage of the input bias transistor. - View Dependent Claims (8, 9, 10, 11, 12)
-
-
13. An apparatus comprising:
-
multi-cascode bias transistors comprising first and second cascode bias transistors and an input bias transistor, the input bias transistor comprising a drain coupled to the source of the first cascode bias transistor; and means for adjusting the bias voltage of at least one of the multi-cascode bias transistors by configuring a configurable impedance; means for selectively decoupling at least one configurable impedance network from a first supply voltage. - View Dependent Claims (14, 15, 16)
-
-
17. A method comprising:
-
generating bias voltages for first and second cascode bias transistors, the generating comprising configuring the impedance of at least one configurable impedance network coupled to a first supply voltage to vary the voltage tapped from an impedance divider network; and coupling the generated bias voltages to first and second cascode transistors, the first and second cascode bias transistors having fixed current ratios relative to the first and second cascode transistors, the source of the first cascode bias transistor coupled to the drain of an input bias transistor, the source of the first cascode transistor coupled to the drain of an input transistor; wherein the input bias transistor is biased to a gate voltage determined by a reference current through a transistor that is a replica of the input bias transistor. - View Dependent Claims (18, 19)
-
Specification