Amplifiers – With periodic switching input-output
Patent
1998-07-30
1999-11-09
Pascal, Robert
Amplifiers
With periodic switching input-output
330 69, 330258, H03F 102
Patent
active
059822309
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
In the past, analog signal processing circuits have been provided by discrete components. In such arrangements the topology of the circuit and the values of the components to be chosen at the outset have to be "correct" for the particular application. Such circuits have a disadvantage that where changes in circuit requirements occur, it may be difficult to reconfigure the circuit to have a different topology.
More recently, analog integrated circuits have been provided. Such circuits aim to include many or all of the required integers within the integrated circuit. However, the cost of making an integrated circuit for each different possible application would be prohibitive, and accordingly it has become known to provide multi-purpose analog integrated circuits otherwise known as integrated circuit analog systems which have circuit portions which can be selectively enabled or disabled to customize the circuit for a particular application, and which have circuit elements which can be programmed to provide, for example, a desired impedance.
SUMMARY OF THE INVENTION
In a known integrated circuit analog system, an array of configurable analog cells, capable of interconnection with other cells of the array, can be individually configured to set various programmable resistors and capacitors in the cells to desired values. The setting circuitry includes amplifiers whose configuration is desirably programmable.
An embodiment of the present invention provides an amplifier circuit suitable for use in integrated circuit analog systems, and having just such a programmable configuration.
According to a first aspect of the present invention there is provided an amplifier circuit comprising a first and a second two-input differential input circuit, the first differential input circuit having first and second input terminals and a second differential input circuit having third and fourth input terminals, the first input terminal being connected to a first circuit input, the fourth input terminal being connected to a fourth circuit input, and programmable circuitry for selectively connecting the second and third input terminals either to second and third circuit inputs respectively, or to the fourth and first input terminals respectively.
According to a second aspect of the present invention there is provided an amplifier circuit comprising a first and a second two-input differential input circuit, the first differential input circuit having first and second input terminals and a second differential input circuit having third and fourth input terminals, the first input terminal being connected to a first circuit input, the fourth input terminal being connected to a fourth circuit input, and programmable circuitry for selectively connecting the second and third input terminals either to second and third circuit inputs respectively, or to the fourth and first circuit inputs respectively or both to a fifth circuit input.
Preferably the first differential input circuit comprises first and second amplifying elements, and the second differential input circuit comprises third and fourth amplifying elements, each said amplifying element having a respective main current path and a control terminal connected to the respective input terminal.
Conveniently each main current path is defined by a pair of main current electrodes, one main current electrode of the first amplifying element and the corresponding main current electrode of the second amplifying element forming a first node, and one main current electrode of the third amplifying element and the corresponding main current electrode of the fourth amplifying element forming a second node.
Preferably the amplifier circuit further comprises connecting circuitry for selectively connecting the first and second nodes together.
Advantageously the amplifier circuit has first bias circuitry for providing a first current path from the first node to a reference potential and for providing a second current path from the second node to the reference potential.
REFERENCES:
patent: 3725818 (1973-04-01), Nurmohamed et al.
patent: 4797631 (1989-01-01), Hsu et al.
patent: 5325069 (1994-06-01), Sundby
patent: 5808513 (1998-09-01), Archer
Choe Henry
Dover Rennie W.
Motorola Inc.
Pascal Robert
LandOfFree
Amplifier circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Amplifier circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Amplifier circuit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1461744