Analog IC Design

Reducing power consumption offers significant advantages for wireless transducers, but our low power amplifier program goes much further. By making the analog circuits smarter as well as more efficient, we can realize far greater benefits through complete system optimisation. Smart amplifiers can reduce the workload and power requirements of the digital signal processing and radio circuits, helping cut overall power consumption significantly.

Our low power program deals with reducing power consumption while improving performance to include ‘smart’ analog functionality. Some of the techniques being developed to make analog circuitry smarter include:

  • Removing signal artefacts such as motion noise. These artefacts can often be bigger than the signals that need to be measured. By removing these artefacts from the incoming signal, power is not wasted amplifying or digitizing these unnecessary signals.
  • Analog assisted processing to reduce sampling during ‘quiet’ signal periods. For example, we know what an ECG signal looks like so by changing the sampling rate between beats, less information needs to be transmitted by radio.
  • Extracting information in the analog domain that helps with signal processing. Simply by passing on some additional information to the digital signal processor, the amount of signal processing required can be significantly reduced.

As well as developing smarter, low power building blocks, the program is also investigating ultra low power (ULP) sensor interfaces, analog to digital converters (ADCs) and management circuits for wireless sensors.

Sensor interfaces

While existing sensor interface technologies can achieve power usage in the mW range, Holst is developing solutions that operate down to only 10s of µW. First designs and silicon for ULP sensor interfaces are expected soon. They focus on the following technologies:

  • ULP capacitive sensor interfaces for accelerometers and capacitive sensors
  • Resonant sensor interfaces for micro-machined gas sensors and chemical sensors

Analog to Digital Converters

Holst Centre is aiming to take analog to digital converter power consumption down to new levels while raising resolution. Our aim is to achieve 10- to 16- bit resolution with very low power. We already have first designs and are working on first silicon.

Power management for wireless sensors

For self-powered devices that draw energy from vibrations or temperature, the power generated is very unstable. To help manage it we are developing:

  • AC:DC rectification circuit solutions for vibrational energy generation
  • DC:DC circuits for thermal energy management
  • DC:DC circuits for indoor photovoltaics for wireless generation

As the amount of power generated by these means is very limited, these management circuits need to consume an absolute minimum of power. Our target is 80% to 90% efficiency, and the first circuits are already available for thermal power generation.

Partners

This program is of interest to manufacturers of wearable or implantable healthcare devices (medical / sports / lifestyle), consumer electronics companies, silicon manufacturers and mixed signal solution providers.