High Linearity Amplifiers
Spectrum Control’s high linearity amplifiers and high IP2 amps offer ultra high linearity amp performance as high as +100 dBm for both receiver chains for high performance defense systems. Spectrum Control’s High IP2 amplifiers offer Push-Pull and Darlington configurations and eliminate the need for any blocking caps or bypass capacitors.
Spectrum Control’s linear RF amplifiers and ultra high IP3 amplifiers offer multiple options for superior subharmonic reduction with Second Harmonic levels of up to +100 dBm. Typical IP3 performance of +61 dBm is matched with high IP2 performance of +75 dBm on surface mount RF amplifier designs. These push pull amplifiers come in both surface mount and SMA connectorized options. High Second Order amplifier performance of +100 dBm or high third order intercept amplifier performance of +61 dBm is married to free tuning to enhance key parameters without additional NRE.
Spectrum Control offers the widest selection of Linear Amplifiers in the market with 100s to choose from, from HF amplifiers to C Band amplifier designs available online. Spectrum Control’s Push Pull amplifier designs are unique, in that our chip & wire hybrid methodology allows customer specified tuning to fine tune gain, noise figure, output power, bandwidth, and other parameters without NRE. These Push Pull amp designs offer unparalleled performance up to 6000 MHz. MIL-PRF-38534 screening is an option for all models, along with Space Grade amplifier and Space Qualified amplifier options for nearly every standard catalog model.
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Comparing High Linearity Topologies
High linearity is a critical requirement in RF front-end design, ensuring low distortion, high intercept points, and improved signal integrity. This note compares three common amplifier topologies — Darlington, Push-Pull, and Parallel — in terms of distortion characteristics, intercept point (IP2, IP3) performance, and other operational trade-offs. It also provides guidance for selecting the appropriate topology for different RF applications.
| Darlington | Push-Pull | Parallel | |
| Distortion | A Darlington circuit does not inherently cancel distortion. Distortion products are directly influenced by transistor design and biasing. | A push-pull circuit naturally cancels even-order harmonics due to balanced configuration, reducing total distortion. | A parallel circuit offers no intrinsic distortion cancellation; distortion depends on device matching and operating point. |
| IP2 (Second Order Intercept) Performance | A Darlington circuit is fundamentally inferior to push-pull due to lack of distortion cancellation. | A push-pull design is excellent IP2 performance, making it ideal for demanding RF systems. | A parallel circuit does not, does not inherently improve IP2. |
| IP3 (Third Order Intercept) Performance | A Darlington design can offer respectable IP3 with careful design. | A push-pull design supports higher output power, better efficiency, and improved load handling. | A parallel design IP3 performance is comparable to Push-Pull when properly implemented. |
| Other Performance Metrics | Lower output impedance and supply current improvements; generally lower efficiency | A push pull circuit supports higher output power, better efficiency, and improved load handling. | A parallel design provides higher output power by combining devices but requires careful current sharing to maintain linearity |
Key Takeaway
- Push-pull designs are advantageous when harmonic suppression is a priority
Application Guidelines
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When IP2 performance is critical. select push-pull topology
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For general gain block requirements where linearity is important, Darlington can be a cost-effective option
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When output power is the sole requirement, parallel topology is best suited
Summary
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Darlington: simple implementation, moderate IP3 performance, but limited IP2
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Push-Pull: best for linearity and harmonic suppression, suitable for high-performance RF systems
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Parallel: best for output power scaling but requires careful design for thermal and current balance; the choice of topology should align with the primary performance requirement: linearity, gain, or output power
Figure 1: Harmonic Distortion: Darlington vs Push-Pull
Figure 2. Relative IP3 Performance by Topology
About Amplifiers
Spectrum Control is a leading provider of high-performance RF amplifier solutions. We design, develop, and manufacture small signal amplifiers. Our standard and custom-designed, high-reliability amplifiers meet emerging military and commercial requirements.
Spectrum Control remains on the cutting edge of amplifier technology through out-of-the-box engineering and the manufacture of designs that reach increasing levels of complexity, power and performance. Spectrum Control can tailor a solution to your unique requirements.
Low phase noise, low noise, ultra high linearity, high frequency, and medium power RF amplifier products are available.