Abstract
In this paper, a study of the operation of switched continuous-time filters (SCTFs), defined as continuous-time filters with elements that are alternatively switched on and off in the signal path, is conducted. A well-known example is the use of switched resistors to multiply their value, but the universe of applications is wider. First, a detailed calculation of the output of an SCTF in the frequency domain, which allows the examination of any SCTF in a general framework, is presented. This result particularly explains the resistor multiplication effect. Three application examples using switched elements are presented and examined as SCTFs: a nonideal sample & hold, a switched active filter that is tuned by varying the duty cycle of the switching, and a switched Gm-C filter to implement a chopper amplifier. In all cases, the theoretical background allows the examination of circuit behavior and limitations, and the analysis is supported by measurements or transient simulations.
| Original language | English |
|---|---|
| Pages (from-to) | 1421-1429 |
| Number of pages | 9 |
| Journal | IEEE Transactions on Circuits and Systems I: Regular Papers |
| Volume | 55 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jul 2008 |
| Externally published | Yes |
Keywords
- Analog processing circuits
- Analog processing circuits example
- Continuous-time filters
- Filter theory
- Frequency-domain analysis
- Over switched- capacitor filters
- Switched systems