Inverse Analog Filters: History, Progress and Unresolved Issues
Abstract
:1. Introduction
2. The Transfer Functions of Inverse Filters, Their Frequency Responses, the Significance of the Various Parameters and the Stability Issues
2.1. Significance of the Coefficients of the Inverse Transfer Functions in the Characterization of Their Frequency Responses
2.2. Stability Considerations
- (i)
- As is well known, if the verification of the workability of the circuit is carried out only by frequency response analysis in SPICE without checking the transient response of the circuits, they may still exhibit the correct frequency responses and, thus, the circuit instability might go unnoticed in the absence of looking into its transient analysis.
- (ii)
- In those cases where experimental results of the frequency responses of such circuits are taken and the circuits are shown to work properly, the possible reason could be that the various parasitics of the active element used or their non-ideal parameters might have shifted the pole locations slightly to the left half of the s-plane (which appear feasible in case of IHP or IBR but unlikely in the case of inverse all-pass filters) and therefore, any instability could not have been observed.
- (iii)
3. Circuit Realizations of the Various Inverse Analog Filters
3.1. IAF Configurations Using Op-Amps and FTFNs
3.2. IAF Configurations Using Four-Terminal-Floating-Nullors (FTFN)
3.3. IAF Configurations Using Current Feedback Operational Amplifiers (CFOA)
3.4. IAF Configurations Using Operational Transconductance Amplifiers (OTA)
Figure 12a ILPF | |
Figure 12b IBPF | |
Figure 12c IHPF |
3.5. IAF Configurations Using Second Generation Current Conveyors (CCII)
3.6. IAF Configurations Using Second Generation Voltage Conveyors (VCII)
3.7. IAF Configurations Using Operational Transresistance Amplifiers (OTRA) and Current Differencing Buffered Amplifiers (CDBA)
3.7.1. OTRA-Based Inverse Active Filters
3.7.2. Inverse Active Filters Employing CDBA
3.8. Inverse Active Filters Employing Current-Differencing Transconductance Amplifier (CDTA)
3.9. Inverse Active Filters Employing Voltage Differencing Transconductance Amplifiers (VDTA)
4. The Unresolved Issues
5. Concluding Remarks
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Reference, Year | Name and Number of ABB Used | Number of G + R + C | Whether All Grounded Capacitors Used | Whether USED ABB Is Available as Off-the-Shelf IC? | Inverse Filter Functions Realized |
---|---|---|---|---|---|
[1] | Op-amp (1) | 0 + 4 + 2 | No | Yes | IHP |
[37] | Op-amp (1) | 0 + (1/2) + (1/2) | No | Yes | IHP #, IBP |
[16] | OTA (5/6) | (5/6) + 0 + 2 | Yes | Yes | ILP, IHP, IBP |
[17] | OTA (4/5) | (4/5) + 0 + 2 | Yes | Yes | ILP, IHP, IBP, IBR |
[18] | CCII (3/4) | 0 + (3/4) + 2 | Yes | Yes | ILP, IHP, IBP |
[19] | CCII (1) | 0 + 2 + 1 | Yes | Yes | IAP # |
[11] | CFOA (3) | 0 + 4 + 2 | Yes | Yes | ILP, IHP, IBP, IBR |
[12] | CFOA (3) | 0 + (3/5) + 2 | Yes | Yes | ILP, IHP, IBP, IBR |
[13] | CFOA (3) | 0 + (2/3) + (2/3) | Yes | Yes | ILP, IHP, IBP |
[15] | CFOA (2) | 0 + (4/6) + 2 | Yes | Yes | ILP, IHP, IBP, IBR |
[14] | MCFOA (3) | 0 + (2/3) + (3/4) | Yes | No | ILP, IHP, IBP |
[7] | FTFN (1) | 0 + 5 + 2 | No | No | ILP |
[8] | FTFN (1) | 0 + 8 + 2 | No | No | IAP |
[9] | FTFN (1) | 0 + 4 + 2 | No | No | ILP, IHP, IBP, IBR, IAP |
[10] | FTFN (1) | 0 + 3 + 1 | No | No | IAP # |
[23] | OTRA (2) | 0 + (4/5) + 2 | No | No | ILP, IHP, IBP |
[24] | OTRA (2) | 0 + (4/6) + (3/4) | No | No | IBR, IAP |
[25] | OTRA (1) | 0 + 3 + 3 | No | No | IBR |
[27] | CDBA (2) | 0 + (2/4) + (2/4) | No | No | ILP, IHP, IBP, IBR, IAP |
[28] | CDBA (2) | 0 + (3/4) + (3/4) | No | No | ILP, IHP, IBP |
[29] | CDBA (2) | 0 + (4/5) + 2 | No | No | IBR, IAP |
[30] | CDBA (2) | 0 + 3 + 2 | No | No | ILP, IHP, IBP, IBR |
[31] | CDBA (2) | 0 + 9 + 9 | No | No | IBPF |
[32] | CDBA (1) | 0 + (2/3) + (2/3) | No | No | ILP, IHP, IBP, IBR |
[33] | CDTA (1) | 0 + 1 + 1 | Yes | No | IAP # |
[34] | CDTA (3) | 0 + 2 + 2 | Yes | No | ILP |
[35] | VDTA (2/4) | (4/8) + 0 + 2 | Yes | No | ILP, IHP, IBP, IBR |
[36] | VDTA (4) | 8 + 0 + 2 | Yes | No | ILP, IHP, IBP, IBR |
[21] | VCII (2/3) | 0 + (4/6) + (1/2) | No | No | ILP #, IHP #, IBP |
[22] | VCII (2) | 0 + 2 + 2 | Yes | Yes | ILP, IHP, IBP, IBR |
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Senani, R.; Bhaskar, D.R.; Raj, A. Inverse Analog Filters: History, Progress and Unresolved Issues. Electronics 2022, 11, 841. https://doi.org/10.3390/electronics11060841
Senani R, Bhaskar DR, Raj A. Inverse Analog Filters: History, Progress and Unresolved Issues. Electronics. 2022; 11(6):841. https://doi.org/10.3390/electronics11060841
Chicago/Turabian StyleSenani, Raj, Data Ram Bhaskar, and Ajishek Raj. 2022. "Inverse Analog Filters: History, Progress and Unresolved Issues" Electronics 11, no. 6: 841. https://doi.org/10.3390/electronics11060841