Proving the Business Case for the Internet of Things

Microsemi radio module suits implantable medical devices

Steve Rogerson
August 11, 2015
Microsemi has introduced the smallest radio module it has ever produced. The ZL70323 is for implantable medical devices such as pacemakers, cardiac defibrillators and neuro-stimulators.
Measuring 5.5 by 4.5 by 1.5mm, the module supersedes the company's ZL70321 and complements its ZL70120 radio module used for external device controllers. Both are based on the company’s low-power ZL70103 radio transceiver chip, which supports a high data rate radio frequency link for medical implantable communications applications.
"Our radio modules allow medical device companies to focus more of their research dollars and development efforts on new therapies that enable a better quality of life," said Martin McHugh, Microsemi's product line manager for the module. “The reduction in size makes it easier for companies to design smaller devices that aid patient comfort and reduce risk of infection, as a smaller incision is needed. RF engineering is a highly specialised discipline and leveraging our deep expertise in this area also allows our customers to reduce design times, reduce time-to-market and minimise project risk."
RF technology is increasingly being used in medical implantable applications including cardiac care, physiological monitoring (for example, insulin), pain management and obesity treatments. According to Roots Analysis Business Research & Consulting, the global neuro-stimulation devices market is likely to achieve sales of $6.5bn by 2017, growing at a CAGR of 17.9 per cent from 2011 to 2017.
The ZL70323 module implements all RF-related functions needed to deploy the implant node in a medical implantable communications service (MICS) RF telemetry system. The integrated antenna tuning circuit lets the module be used with a wide range of implantable antennas (nominal antenna impedance is 100+j150Ω). The module provides the following major blocks:

  • MICS-band RF transceiver with integrated matching network, surface acoustic wave (SAW) filter for suppression of unwanted blockers, and antenna tuning;
  • 2.45GHz wake-up receiver matching network;
  • Integrated 24MHz reference frequency crystal; and
  • Decoupling capacitors and series termination resistors.
The products are aimed at letting patient health and device performance data be quickly transmitted with little impact to the battery life of the implanted device. The device operates in the 402 to 405MHz MICS band.
Multiple low power wake-up options are supported including using an ULP 2.45GHz industrial, scientific and medical (ISM) band wake-up receive option. The ZL70103 consumes less than 6mA when transmitting or receiving and consumes 290nA when in a periodic sleep and sniff mode with one second sniff intervals.