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Element Superposition Based Efficient PGA Gain Step Testing

IP.com Disclosure Number: IPCOM000031285D
Published in the IP.com Journal: Volume 4 Issue 10 (2004-10-25)
Included in the Prior Art Database: 2004-Oct-25
Document File: 2 page(s) / 57K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

The gains in programmable gain amplifier (PGA) circuits are achieved by implementing a network of elements (e.g. resistors, capacitators or current sources) and switches. By changing the configuration of the switches (on/off) the individual gain settings can be applied. The total number of switch settings is 2n, with n being the number of switches. Up to now, for testing the device every single switch setting is programmed and the analog output (the gain) is measured to verify functionality and accuracy. So the amount of time required to test the device increases linearly with the number of gain settings and therefore exponentially with the number of switches. For complex PGAs with many settings the test costs can rise considerably. Sometimes the test costs are being reduced by measuring only a few or even just one gain setting. Hence the device is not fully checked.

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Element Superposition Based Efficient PGA Gain Step Testing

Idea: Fan Yung Ma, SG-Singapore

The gains in programmable gain amplifier (PGA) circuits are achieved by implementing a network of elements (e.g. resistors, capacitators or current sources) and switches. By changing the configuration of the switches (on/off) the individual gain settings can be applied. The total number of switch settings is 2n, with n being the number of switches.

Up to now, for testing the device every single switch setting is programmed and the analog output (the gain) is measured to verify functionality and accuracy. So the amount of time required to test the device increases linearly with the number of gain settings and therefore exponentially with the number of switches. For complex PGAs with many settings the test costs can rise considerably. Sometimes the test costs are being reduced by measuring only a few or even just one gain setting. Hence the device is not fully checked.

It is therefore proposed to reduce the number of tests by exploiting the fact that every element in the network can be a part of different gain settings. The number of necessary tests can be reduced drastically by selecting a sub-set of gain settings such that every element and switch is participating in a test at least once. Additionally the tests in which only elements are used that have been tested before can be skipped.

As an example figure 1 shows a single stage PGA having seven switched resistor elemen...