**2.1.2 Miniaturized antenna**

226 Modern Telemetry

out-of-band rejection. Zero level packaging ensures a micro-cavity on the upper side of the

The filter is based on a double-lattice topology (Fig. 3 (a)) and series inductances of maximum 1nH can be added so as to increase slightly the bandwidth, or for matching considerations. The photography in Fig. 3 (b) shows the 2.4 GHz filter. The active area is 450x225µm2, and the complete die is 1mm2. 120µm diameter areas with a 150µm pitch were

(a) (b)

Flip-chip on CMOS and LTCC technologies were studied for the integration of the filter. As illustrated in Fig. 4 (a), flip chip on CMOS integration approach exhibits limited performances for several reasons. The CMOS technology is based on a lossy substrate which give low performances interconnects. As consequences, wide pad bumps are strongly capacitive and minimum distance between bumps and pad ring gives long and lossy lines.

 (a) (b) Fig. 4. BAW filter responses (a) Flip chip on CMOS measurement and simulation (b) Stand

resonator, thanks to a released bi-layer SiO2/BCB.

prepared for bumping as well as for probe testing.

**100** Ω **100** Ω

Fig. 3. Double lattice BAW filter (a) topology (b) photography

alone BAW filter versus flip chip on LTCC

A miniaturized loop antennas for implanted medical device designed to operate at both MICS 402-405 MHz and ISM 2.4 GHz frequency bandwidths have been successfully fabricated [18-21]. As illustrated in Fig. 5, the designed rectangular loop antenna embedded in a titanium (σ=2.3×106 S/m) housing biocompatible pacemaker prototype is made of copper (σ=5.8×107 S/m) covered with a silicone layer (εr=2.8) for biocompatibility. The physical dimensions of the rectangular loop antenna are approximately equal to 29.5 mm width and 18 mm height.

Fig. 5. Miniaturized loop antenna embedded in a pacemaker prototype
