Over the past two decades, AnaPico has introduced several analog signal generator series to the market, including the APSIN, APULN and APLC, each progressively improving performance aspects. Continuing this tradition, AnaPico presents the APHSP series signal generators. This new series boasts the best phase noise, spectral purity performance and switching time in the market. The APHSP signal generators are available in single- and multi-channel versions, with options for compact desktop units and 19 in. rack-mountable forms.

EXCEPTIONAL PERFORMANCE BENCHMARKS

The AnaPico APHSP signal generator series specifications:

  • Frequency range: 1 kHz/10 MHz to 12.75/20/40/51 GHz with a 0.001 Hz setting resolution
  • Output power range: -120 to +20 dBm with a 0.1 dB setting resolution
  • SSB phase noise: -139 dBc/Hz at 20 kHz offset from a 10 GHz carrier with single-digit femtosecond RMS jitter
  • Switching time/sweep time step: < 5 μs with the FS (fast-switching) option
  • Spurious signals: -70 dBc
  • Harmonics and subharmonics: -60 dBc
  • Modulations: Accurate analog and pulse modulations
  • Multi-channel models: Strongly phase-coherent
  • Reference input/output: 10/100/3000 MHz, including a 3 GHz clock for phase-coherent synchronization among multiple devices
  • Dimensions and weight:
    • Single-channel model: 232 × 393 × 97 mm (half-width of 19 in.); weight: < 10 kg
    • Multi-channel model: 19 in. and 2 HU rack-mountable module; weight: < 18 kg
  • Power consumption: 80 W (single channel)
  • Communication ports: ETHERNET, USB, GPIB.

Figure 1 shows the APHSP signal generator phase noise performance across several frequencies up to 100 MHz offset. This outperforms all other analog signal generators currently on the market. Beyond the 1 MHz offset, the APHSP maintains agility with a switching time below 5 µs due to avoiding a phase-locked loop (PLL) for noise suppression. This characteristic is shared with other models in our analog signal source lineup.

Figure 1

Figure 1 APHSP SSB phase noise at 10 dBm Pout.

INNOVATIVE DESIGN MEASURES

The APHSP signal generator architecture is based on fully direct synthesis, so it uses a PLL only for synchronization with external reference sources. The PLL has been central to high spectral-quality frequency synthesis for many decades thanks to its narrowband filtering capability. However, addressing the excessive noise inherent to PLL systems has been a persistent challenge, often at the cost of increased system power consumption and expense. While AnaPico has traditionally adhered to conventional frequency synthesis principles, it continuously innovates. Achieving a new qualitative level in microwave generation often necessitates choosing between direct and indirect synthesis. Recent advancements in direct digital synthesis chips, frequency dividers and high rejection microwave filters have created new opportunities to develop efficient and compact direct-frequency synthesizers.

The APHSP series utilizes direct digital synthesis in the UHF range, where the signal spectrum quality is inherently high and the frequency switching time and step are intrinsically minimal. This UHF range is then up-converted in steps over an octave, maintaining low non-harmonic components and phase noise. This synthesis approach leverages the noise performance of high frequency oven-controlled crystal oscillator (OCXOs) without significant degradation. However, generating a system reference signal with minimal phase noise presents a new challenge. AnaPico addresses this with a proprietary solution that produces the 3 GHz reference signal shown in Figure 2, which can be used in frequency synthesis and is accessible via the rear panel. This solution includes low noise frequency multipliers and custom-designed oscillators, such as a 100 MHz OCXO. Maintaining the noise potential of quartz at microwave frequencies below -180 dBc/Hz is notably challenging when using commercial off-the-shelf OCXOs.

Figure 2

Figure 2 Phase noise of 3 GHz reference clock.

The synthesized frequency range is extended from 1 kHz to 51 GHz using multipliers and frequency dividers. Then, power amplification, harmonic suppression and output level stabilization are performed across the entire frequency and temperature ranges.

The PLL is retained only for synchronization with external reference signals, ensuring the specified noise performance regardless of the external reference source quality. When a high-quality external signal (e.g., a 10 MHz generator with the LN option) is used, standard settings of 10 or 100 MHz can be used, implementing a PLL bandwidth of about 50 Hz. For synchronization with a stable but noisy source like an Rb oscillator, the VREF option is more suitable, offering a bandwidth of less than 1 Hz. The installed LN option eliminates the need for users to seek a low noise oscillator, providing the best available phase stability. The VREF option allows for enhanced accuracy and long-term frequency stability using atomic frequency standards without compromising phase noise. The combination of VREF and LN options achieves a reference PLL bandwidth of 0.05 to 0.1 Hz.

APPLICATIONS

Phase-coherent single- and multi-channel analog signal generators with ultra-low phase noise, very high spectral purity and fast-switching capabilities have a wide range of potential applications. Some applications that are enabled by sophisticated multi-channel signal generators with high spectral purity and excellent phase coherence include:

  • MIMO and beamforming networks in wireless communication systems
  • Radar and electronic warfare systems that drive arrays or jam and deceive enemy systems
  • Quantum computing and research that are exploring qubit control and quantum protocols
  • Fundamental scientific research and metrology to enable interferometry, spectroscopy and timing systems
  • Medical imaging and diagnostics to improve MRI and ultrasound imaging capabilities
  • Test and measurement equipment that enables the evolution of RF and microwave components
  • Navigation and satcom opportunities in aerospace and defense that depend on precise, high-quality signal generation
  • Advanced driver-assistance systems and vehicle-to-everything opportunities in automotive where radar and communications systems are becoming critical
  • Industrial and environmental monitoring to expand measurement capabilities
  • Education and training to enable the next generation of academic and industrial advances.

In summary, single- and phase-coherent multi-channel analog signal generators with ultra-low phase noise, high spectral purity and fast-switching capabilities are invaluable in any application where precise, reliable signal generation is essential. They enable advancements in technology and research, ensuring high performance and accuracy in a wide range of critical and cutting-edge applications.

AnaPico AG
Glattbrugg, Switzerland
www.anapico.com