Rail splitting virtual ground generator for single supply systems
First Claim
1. A rail splitting virtual ground generator circuit, comprising:
- first and second resistors, coupled to an voltage reference node and further coupled between first and second supply voltages, operable such that a predetermined reference voltage is available at the voltage reference node;
a bias current source coupled to said first supply voltage;
an operational amplifier coupled to said reference voltage in a unity gain configuration, having an output coupled to an output terminal, and powered by said bias current source and said second supply voltage;
a noise reduction input coupled to said reference voltage; and
operable to provide a stable voltage at the output terminal which is equal to half the difference between said first and second supply voltages over a wide range of supply voltage and temperature conditions.
0 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for a circuit physically realizing a virtual ground function producing a virtual ground voltage halfway between the supply and common voltages and having improved accuracy and stability is described. A stable bias current source is coupled to a precision resistor voltage divider network, which is used as a voltage reference generator to produce a virtual ground voltage of a precise value. This reference voltage is coupled to an operational amplifier configured in a unity gain configuration. The circuit thus created offers numerous advantages over the virtual ground circuits in use in the prior art. An integrated circuit implementing this circuit is described, and alternative packaging embodiments are disclosed. Other embodiments are also disclosed.
28 Citations
30 Claims
-
1. A rail splitting virtual ground generator circuit, comprising:
-
first and second resistors, coupled to an voltage reference node and further coupled between first and second supply voltages, operable such that a predetermined reference voltage is available at the voltage reference node; a bias current source coupled to said first supply voltage; an operational amplifier coupled to said reference voltage in a unity gain configuration, having an output coupled to an output terminal, and powered by said bias current source and said second supply voltage; a noise reduction input coupled to said reference voltage; and operable to provide a stable voltage at the output terminal which is equal to half the difference between said first and second supply voltages over a wide range of supply voltage and temperature conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method for creating a virtual ground reference voltage for use in a single supply system, comprising the steps of:
-
providing a pair of precision resistors coupled between a first and second voltage supply; providing a temperature stable bias current source coupled to said first voltage supply; providing an operational amplifier having increased current drive capability, powered by said bias current source and said second voltage supply; coupling a predetermined reference voltage produced by the said pair of precision resistors one input terminal of said operational amplifier; coupling the output of said operational amplifier to a voltage output terminal, and further coupling said voltage output terminal to a second input terminal of said operation amplifier; and operating said operational amplifier in a unity gain configuration so as to provide a voltage at the voltage output terminal that is one half the difference in said first and second supply voltages. - View Dependent Claims (14, 15, 16)
-
-
17. An integrated circuit implementing a virtual ground reference voltage circuit, comprising:
-
first and second voltage supply terminals; a voltage output terminal; first and second resistors, coupled to an voltage reference node and further coupled between said first and second supply voltages, operable such that a predetermined reference voltage is available at the voltage reference node; a bias current source coupled to said first supply voltage; an operational amplifier coupled to said reference voltage in a unity gain configuration, having an output coupled to said output terminal, and powered by said bias current source and said second supply voltage; a noise reduction input coupled to said reference voltage; and operable to provide a stable voltage at the output terminal which is equal to half the difference between said first and second supply voltages over a wide range of supply voltage and temperature conditions. - View Dependent Claims (18)
-
-
19. A rail splitting virtual ground generator circuit, comprising:
-
a resistor voltage divider coupled between first and second supply voltages operable to provide a predetermined reference voltage; a bias current source coupled to said first supply voltage; an amplifier coupled to said reference voltage and having an output coupled to an output terminal, said amplifier being powered by said bias current source; and operable to provide a stable voltage at the output terminal which is equal to half the difference of said first and second supply voltages. - View Dependent Claims (20, 21, 22, 23, 24, 25)
-
-
26. A method for creating a rail splitting virtual ground generator circuit, comprising the steps of:
-
providing a resistor voltage divider coupled between first and second supply voltages operable to provide a reference voltage; providing a bias current source coupled to said first supply voltage; providing an amplifier coupled to said reference voltage and having an output coupled to an output terminal, said amplifier being powered by said bias current source; and operating said amplifier and bias current source to provide a stable voltage at the output terminal which is equal to half the difference of said first and second supply voltages. - View Dependent Claims (27, 28, 29, 30)
-
Specification